1. Field of the Invention
This invention relates to milling-drilling section billets and particularly to milling-drilling section billet and anchoring devices.
2. Description of the Prior Art
Systems have been developed in oil well construction that allow drillers to depart, angularly, from an existing open-hole section of wellbore. One method to do this uses an aluminum cylinder that is connected to an anchoring device. The assembly is carried into the wellbore on drill pipe, tubing or coiled tubing that is connected to a commonly available industry standard hydro-mechanical setting tool, which is connected to the aluminum cylinder and anchoring device with a frangible member. The function of the setting tool is to convert the force supplied by hydraulic pumps, pumping against a closed system within the bore of the carrying pipe, against piston areas within the setting tool that convert this force into mechanical movement/action.
The assembly is carried into the wellbore and positioned within the open-hole section of the wellbore. Upon activation of the setting tool, the anchoring device expands some type of retention locking slips along its axis and forces them outwards against an angular cone, which contacts the bore wall and anchors the assembly in place. This mechanical activation of the anchoring device along with the slip configuration geometry causes the assembly to pivot about a point, which then causes the assembly to pivot axially along the wellbore, forcing the top of the aluminum cylinder to cantilever over until it contacts the borehole. Upon contact of the locking slips with the bore wall, the billet is locked against the bore wall and, consequently, no further axial motion is permitted within the aluminum cylinder and anchoring device. This transfers any additional axial loading into the frangible member, which fails upon reaching its maximum load bearing capacity. At the point when fracture occurs, the setting tool separates from the aluminum cylinder and anchoring device. The setting tool is then retrieved to surface, leaving the billet locked in place within the wellbore. The setting too is replaced with a drilling bottom hole assembly to continue the drilling operation.
Subsequent drilling bottom hole assemblies are then deployed and using the aluminum cylinder as a hard deflection device (as compared to the softer formation) the drilling bottom hole assembly is deflected onto a new drilling path that is more favorable to the operation and wellbore trajectory requirements.
One example of such a device is found in U.S. Pat. No. 6,695,056.